Referring to FIG. 10, there are shown cross-sectional views illustrating operations of an oscillating type rotorsco pump of the related art.
As shown, a rotorsco pump includes a camshaft 64 which is eccentrically connected to a rotating shaft 63 of a motor to be eccentrically rotated by rotation of the motor, a rotor 61 which is eccentrically rotated while sliding on an inner wall of an outer casing 62 by rotation of the camshaft 64, and an oscillating shaft 60 which is positioned on a line bisecting the rotor 61 and serves as a centering shaft of the rotor 61.
In operations of the rotorsco pump of the related art, constructed as mentioned above, if the camshaft 64 is eccentrically rotated by the rotation of the motor, the rotor 61 is also eccentrically rotated to compress and discharge fluid. At this time, while an angle formed by the oscillating shaft 60 for one revolution of the rotor 61 is changed from 0 to .alpha. or .beta., torque is produced at a contact point between the oscillating shaft 60 and the rotor 61. By this, it is difficult to control eccentricity of the rotor 61, and as abrasion of the camshaft 64 and a bearing progresses, friction between the rotor 61 and the inner wall of the outer casing 62 is augmented.
As another fluid pump, a scroll compressor of which the driving type is modified not to rotational reciprocating movement, but to pivoting movement, is disclosed in the art. However, the scroll compressor suffers from defects in that workability is deteriorated because of a complicated scroll curve and a larger fluid capacity cannot be achieved due to a limitation in machining the scroll curve to a sufficient depth. Further, when abrasion of a crankshaft and a bearing is generated, abrasion and fracture are caused between scrolls. Accordingly, because maintenance must be thoroughly carried out, a great deal of effort and time is needed.